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Abstract(s)
Ao longo dos anos tem-se verificado uma constante evolução nos diferentes materiais
desenvolvidos para a indústria e nos processos de maquinagem por arranque de apara. O
desenvolvimento de ferramentas de corte com recurso à aplicação de revestimentos avançados
tem sido de grande importância, pois permite aumentar o tempo de vida das ferramentas de corte,
ao mesmo tempo que a qualidade da superfície das peças é assegurada de forma mais efetiva. Em
determinados casos, permite mesmo diminuir os custos de produção. Devido ao desenvolvimento
contínuo de uma enorme variedade de revestimentos, torna-se fulcral analisar, conhecer, e estudar
os fenómenos originados durante o corte de metais, de forma a permitir: i) selecionar os
parâmetros de corte a usar para maquinar determinados materiais e ii) perceber e estimar o tempo
de vida das ferramentas.
O principal objetivo desta tese é avaliar os mecanismos de desgaste, para a qual se sujeitará um
conjunto de ferramentas a um revestimento, com o intuito de maquinar uma liga cobre-berílio,
tendo por base um processo de deposição física em fase de vapor.
Os ensaios a realizar tiveram como principal objetivo avaliar o comportamento das ferramentas
que foram usadas na fresagem para este tipo de ligas, fazendo variar dois parâmetros,
nomeadamente o comprimento de corte e a velocidade de avanço, em três níveis distintos. Para
além disto, foi analisada a rugosidade superficial para cada ensaio realizado, tendo sido também
identificados os mecanismos de desgaste observados.
Após a realização dos mesmos, foi verificado que os resultados obtidos nas ferramentas revestidas
foram distintos dos obtidos com as ferramentas sem revestimento. Nas ferramentas não revestidas,
os principais mecanismos de desgaste foram a abrasão e adesão ao substrato, sendo que nas
ferramentas não revestidas o mecanismo predominante foi a delaminação, seguida do chipping.
Verificou-se ainda que tanto a velocidade de avanço como o comprimento de corte são dois
parâmetros que têm muita influência na qualidade da superfície maquinada, ou seja, quanto maior
for a distância de corte, pior será a qualidade da superfície. Relativamente ao revestimento,
verificou-se que as ferramentas revestidas obtiveram um desempenho muito inferior às sem
revestimento, concluindo-se assim que o revestimento não constituiu um fator vantajoso à
ferramenta.
Over the years, there has been a constant evolution in the different materials developed for industry and in the machining processes. The development of cutting tools using the application of advanced coatings has been of great importance, as it allows the lifespan of cutting tools to be increased, while at the same time the surface quality of the parts is ensured more effectively. In certain cases, it even allows production costs to be reduced. Due to the continuous development of a huge variety of coatings, it is essential to analyze, understand and study the phenomena arising during the cutting of metals, in order to allow: i) selecting the cutting parameters to be used to machine certain materials, and ii) understand and estimate the lifespan evolution of tools in those machining processes. To this end, it is essential to analyze, understand and deepen knowledge regarding the respective associated wear mechanisms, to monitor this development and thus make a positive contribution to the scientific community. The main objective of this dissertation is to evaluate the wear mechanisms, for which a set of tools will be subjected to a coating based on a physical deposition process in the vapor phase, with the aim of machining a copper-beryllium alloy. The main objective of the tests to be carried out was to evaluate the behavior of the tools used in milling for this type of alloys, varying two parameters, namely feed rate and cutting length at three different levels. In addition, the surface roughness was analyzed for each test carried out, and the observed wear mechanisms were also identified. After carrying out the tests, it was verified that the results obtained with coated tools were different from those obtained with uncoated tools. In uncoated tools, the main wear mechanisms were abrasion and adhesion to the substrate, while in uncoated tools the predominant wear mechanism was delamination of the coating, followed by chipping. It was also found that both the feed rate and the cutting length are two parameters that have presented a great influence on the quality of the machined surface, i.e., the higher the cutting length, the worse the surface quality. Regarding the coating, it was found that the coated tools performed much worse than the uncoated ones, concluding that the coating did not constitute an advantageous factor for the tool.
Over the years, there has been a constant evolution in the different materials developed for industry and in the machining processes. The development of cutting tools using the application of advanced coatings has been of great importance, as it allows the lifespan of cutting tools to be increased, while at the same time the surface quality of the parts is ensured more effectively. In certain cases, it even allows production costs to be reduced. Due to the continuous development of a huge variety of coatings, it is essential to analyze, understand and study the phenomena arising during the cutting of metals, in order to allow: i) selecting the cutting parameters to be used to machine certain materials, and ii) understand and estimate the lifespan evolution of tools in those machining processes. To this end, it is essential to analyze, understand and deepen knowledge regarding the respective associated wear mechanisms, to monitor this development and thus make a positive contribution to the scientific community. The main objective of this dissertation is to evaluate the wear mechanisms, for which a set of tools will be subjected to a coating based on a physical deposition process in the vapor phase, with the aim of machining a copper-beryllium alloy. The main objective of the tests to be carried out was to evaluate the behavior of the tools used in milling for this type of alloys, varying two parameters, namely feed rate and cutting length at three different levels. In addition, the surface roughness was analyzed for each test carried out, and the observed wear mechanisms were also identified. After carrying out the tests, it was verified that the results obtained with coated tools were different from those obtained with uncoated tools. In uncoated tools, the main wear mechanisms were abrasion and adhesion to the substrate, while in uncoated tools the predominant wear mechanism was delamination of the coating, followed by chipping. It was also found that both the feed rate and the cutting length are two parameters that have presented a great influence on the quality of the machined surface, i.e., the higher the cutting length, the worse the surface quality. Regarding the coating, it was found that the coated tools performed much worse than the uncoated ones, concluding that the coating did not constitute an advantageous factor for the tool.
Description
Keywords
Milling Wear mechanisms TiAlTaN film Coatings Surface roughness AMPCO alloy